Effective method for transmitting control information during the combination of multiple carriers for wideband support

ABSTRACT

The present invention relates to wideband wireless access system, and more particularly to an effective method for transmitting control information during the combination of multiple carriers. As one embodiment of the present invention, there is provided a method by which a base station allocates a carrier to a terminal in a wideband wireless access system supporting multiple carriers, the method comprising: transmitting, to the terminal, a terminal specific or terminal group specific carrier allocation information that includes information about at least one of control information and data; and transmitting, to the terminal, a carrier combination control information that includes information about a change in the at least one candidate carrier available.

FIELD OF THE INVENTION

The present invention related to a wideband wireless access system and,more particularly, to an effective method for transmitting controlinformation during the combination of multiple carriers.

BACKGROUND ART

Hereinafter a Carrier will be briefly described.

A user may include information that the user wishes to transmit byperforming modulation operations on amplitude, frequency, and/or phaseof a sine wave or a periodic pulse wave. At this point, the sine wave orpulse wave, which performs the function of carrying information, isreferred to as a carrier.

Methods for modulating carriers may include an SCM (Single-CarrierModulartion scheme) or an MCM (Multi-Carrier Modulation scheme). Herein,the Single-Carrier Modulation scheme (SCM) refers to a modulationscheme, wherein all types of information is loaded in a single carrierand then modulated.

The Multi-Carrier Modulation scheme refers to a modulation techniquethat can divide a whole Bandwidth Channel of a single carrier intomultiple sub-channels each having a small bandwidth and that can performmulti-transmission through a plurality of narrowband Sub-Carriers.

At this point, when using the Multi-Carrier Modulation (MCM) scheme,each sub-channel may be approximated to a Flat Channel fur to the smallbandwidth. Additionally, the user may compensate for any channeldistortion by using a simple equalizer. Furthermore, high-speedimplementation of the Multi-Carrier Modulation scheme may be performedby using Fast Fourier Transform (FFT). In other words, the Multi-CarrierModulation scheme is more advantageous in high-speed data transmissionas compared to the Single-Carrier Modulation (SCM) scheme.

As the functions of base stations and/or user equipments evolve, thefrequency bandwidth that can be provided by or used in the base stationsand/or user equipments is expanding. Therefore, according to theexemplary embodiments of the present invention, the present inventiondiscloses a multi-carrier system that supports wideband by performingCarrier aggregation, wherein one or more carriers are combined and used(or aggregated).

More specifically, unlike the above-described Multi-Carrier ModulationScheme, wherein a single carrier is divided and shared, themulti-carrier system that will be described below corresponds to thecase when one or more carriers are combined (or grouped) and used.

In order to efficiently use the Multi-Band (or Multi-Carrier), atechnique of having a single Medium Access Control (MAC) entity managemultiple carriers (e.g., multiple Frequency Carriers (FCs)) has beenproposed.

(a) and (b) of FIG. 1 illustrate a method for transmitting and receivingmultiple bandwidth Radio Frequency (RF) based signals.

As shown in FIG. 1, in the transmitting end and in the receiving end, inorder to efficiently use multiple carriers, one Medium Access Control(MAC) layer may manage multiple carriers. At this point, it is assumedthat, in order to efficiently transmit and receive multiple carriers,the transmitting and the receiving end can transmit and receive all ofthe multiple carriers. At this point, since the Frequency Carriers(FCs), which are managed by a single Medium Access Control (MAC) layer,are not required to be contiguous to one another, this technique is moreflexible in the aspect of resource management. More specifically,Contiguous Aggregation and Non-contiguous Aggregation may both beperformed.

Referring to (a) and (b) of FIG. 1, Physical Layer (PHY) 0, PhysicalLayer (PHY) 1, . . . Physical Layer (PHY) n−2, Physical Layer (PHY) n−1indicate the multi-band according to technique of present invention, andeach band may have a frequency carrier (FC) size, which is assigned fora specific service based upon a pre-decided frequency policy. Forexample, Physical Layer 0 (RF carrier 0) may have a frequency carrier(FC) size, which is assigned for general FM radio broadcasting, andPhysical Layer 1 (RF carrier 1) may have a frequency carrier (FC) size,which is assigned for mobile phone communication.

As described above, depending upon the characteristics of each frequencyband, each of the frequency bands may have a different frequency bandsize. However, in the following description, it is assumed that eachfrequency carrier (FC) has a size of A [MHz]. Also, each frequencyallocation band may be represented as a carrier frequency enabling eachfrequency band to use a baseband signal. Hereinafter, each frequencyallocation band will be referred to as a “Carrier Frequency Band” or,when there is no confusion, each frequency allocation band will bemerely referred to as a “Carrier”, which represents each carrierfrequency band. Furthermore, as in the recent 3GPP LTE-A, theabove-described carrier may also be referred to as a “component carrier”in order to be differentiated from the subcarrier, which is used in themulti-carrier scheme.

In this aspect, the above-described “Multi-Band” scheme may also bereferred to as a “Multi-Carrier” scheme or a “carrier aggregation”scheme.

In order to transmit a signal through a multi-band, as shown in (a) ofFIG. 1, and in order to receive a signal through a multi-band, as shownin (b) of FIG. 1, the transmitter/receiver is/are required to include aradio frequency (RF) module, which is configured to transmit and receivesignals through all of the multi-band. Also, referring to FIG. 1, aconfiguration method of “Medium Access Control” is decided by the basestation regardless of a downlink (DL) and an uplink (UL).

In short, the technique of the present invention refers to a techniquefor transmitting/receiving signals by having a single medium accesscontrol entity to manage/operate multiple radio frequency carriers (RFcarriers). RF carriers being managed by a single medium access controlare not required to be contiguous to one another. Therefore, accordingto the technique of the present invention, the multi-band scheme isadvantageous in that it is more flexible in the aspect of resourcemanagement.

FIG. 2 illustrates an exemplary method for allocating a frequency in amulti-carrier system.

Referring to FIG. 2, frequency carrier 0 to frequency carrier 7 may bemanaged by radio frequency 0 to radio frequency 7. Also, as shown in theexample shown in FIG. 2, it is assumed that frequency carrier 0,frequency carrier 2, frequency carrier 3, frequency carrier 6, andfrequency carrier 7 are already assigned to each specific conventionalcommunication service. Meanwhile, available frequency carrier 1,frequency carrier 4, and frequency carrier 5 may be effectively managedby a single medium access control (medium access control #5). Herein, asdescribed above, since the frequency carriers configuring a singlemedium access control are not required to be contiguous to one another,the frequency resource may be more effectively managed.

However, the above-described multi-band based communication scheme mayonly be defined more or less conceptually, and, whenever required, themulti-band based communication scheme may be understood as a methodwherein merely more frequency carriers are additionally assigned.Therefore, an efficient method for transmitting and receiving signalsthat enables high-performance processing, and, more particularly, amethod for transmitting and receiving control information, which newlyor additionally assigned a carrier to the user equipment, or whichmanages the assigned carriers is required to be defined morespecifically.

DETAILED DESCRIPTION OF THE INVENTION Technical Objects

An object of the present invention is to provide an efficientcommunication system and an efficient communication method.

Another object of the present invention is to provide an efficientmethod for transmitting and receiving control information in amulti-band based communication environment.

A further object of the present invention is to provide an efficientmethod for dynamically or semi-statically assigning available carriersto a user equipment via lower layer signaling in a multi-band basedcommunication environment.

The technical objects of the present invention will not be limited onlyto the objects described above. Accordingly, additional technicalobjects of the present application will be set forth in part in thedescription which follows and in part will become apparent to thosehaving ordinary skill in the art upon examination of the following ormay be learned from practice of the present application.

Technical Solutions

In order to achieve the technical objects of the present invention, thepresent invention discloses efficient methods for transmitting andreceiving control information is a wireless communication system usingmulti carriers.

According to an aspect of the present invention, a method for assigninga carrier from a base station to a user equipment in a wideband radioaccess system supporting multiple carriers includes the steps oftransmitting user equipment (UE)-specific or user equipment(UE)-group-specific carrier assignment information to the userequipment, wherein the UE-specific or UE-group-specific carrierassignment information includes information on at least one availablecandidate carrier, the candidate carrier enabling the user equipment totransmit and receive at least one of control information and data, andtransmitting carrier aggregation control information to the userequipment, wherein the carrier aggregation control information includesconfiguration or status change information of the at least one availablecandidate carrier.

At this point, it may be preferable to transmit the carrier assignmentinformation to the user equipment by using higher layer controlsignaling, to transmit the carrier aggregation control information tothe user equipment by using lower layer control signaling.

Also, it may be preferable to semi-statically transmit the carrierassignment information to the user equipment, and to dynamicallytransmit, or to transmit as required, the carrier aggregation controlinformation to the user equipment at a predetermined cycle period byusing an event-triggering method.

Also, the carrier aggregation control information may include at leastone of information on at least one new carrier, the new carrier beingadded to or excluded from the at least one available candidate carrier,information indicating whether or not at least a portion of the at leastone available candidate carrier is activated, and information on a linkchange of the at least one available candidate carrier.

Also, all of at least one user equipment-specific carrier, within a userequipment, a user equipment group, or a base station region, may beconfigured without requesting any separate carrier assignmentinformation, and by using such carrier, configuration information onavailable candidate carriers and/or carrier status change informationand/or link change information may be transmitted as the carrieraggregation control information.

Also, the carrier assignment method may include receiving feedbackinformation from the user equipment, wherein the feedback informationindicates whether or not an error occurs during a reception of thecarrier aggregation control information.

Furthermore, it may be preferable that the step of transmitting thecarrier assignment information is performed after establishing a radioresource control connection between the user equipment and the basestation.

In another aspect of the present invention, a method for receiving acarrier assignment in a user equipment from a base station in a widebandradio access system supporting multiple carriers includes the steps ofreceiving user equipment (UE)-specific or user equipment(UE)-group-specific carrier assignment information from the basestation, wherein the UE-specific or UE-group-specific carrier assignmentinformation includes information on at least one available candidatecarrier, the candidate carrier enabling the user equipment to transmitand receive at least one of control information and data, and receivingcarrier aggregation control information from the base station, whereinthe carrier aggregation control information includes configuration orstatus change information of the at least one available candidatecarrier.

At this point, it may be preferable that the carrier assignmentinformation is received by using higher layer control signaling, andthat the carrier aggregation control information is received by usinglower layer control signaling.

Also, it may be preferable that the carrier assignment information issemi-statically received, and that the carrier aggregation controlinformation is dynamically received, or received as required, at apredetermined cycle period by using an event-triggering method.

Also, it may be preferable that the carrier aggregation controlinformation includes at least one of information on at least one newcarrier, the new carrier being added to or excluded from the at leastone available candidate carrier, information indicating whether or notat least a portion of the at least one available candidate carrier isactivated, and information on a link change of the at least oneavailable candidate carrier.

Additionally, the carrier assignment method may further includetransmitting feedback information to the base station, wherein thefeedback information indicates whether or not an error occurs during areception of the carrier aggregation control information.

Furthermore, the user equipment may operate in accordance with thecarrier aggregation control information, after a predetermined number ofsub-frames, starting from a point where the carrier aggregation controlinformation is received.

In yet another aspect of the present invention, a mobile user equipmentoperating in a wideband radio access system supporting multiple carriersmay include a processor, and a radio communication module configured toreceive a radio signal from an external source, to perform demodulationand decoding on the received radio signal, and to deliver the processedsignal to the processor, and configured to perform modulation andencoding on data being delivered from the processor and to transmit theprocessed data to an external target. Herein, the processor may receiveuser equipment (UE)-specific or user equipment (UE)-group-specificcarrier assignment information from a base station, so as to acquireinformation on at least one available candidate carrier, which is usedfor transmitting and receiving at least one of control information anddata, and the processor may receive carrier aggregation controlinformation from the base station, so as to decide an available carrierbased upon configuration or status change information of the at leastone available candidate carrier included in the received carrieraggregation control information, thereby enabling the mobile userequipment to communicate with the base station.

At this point, it may be preferable to receive the carrier assignmentinformation by using higher layer control signaling, and it may bepreferable to receive the carrier aggregation control information byusing lower layer control signaling.

Also, the carrier assignment information may be semi-staticallyreceived, and the carrier aggregation control information may bedynamically received, or received as required, at a predetermined cycleperiod by using an event-triggering method.

Also, the carrier aggregation control information may include at leastone of information on at least one new carrier, the new carrier beingadded to or excluded from the at least one available candidate carrier,information indicating whether or not at least a portion of the at leastone available candidate carrier is activated, and information on a linkchange of the at least one available candidate carrier.

And, the processor may determine whether or not an error occurs whenreceiving the carrier aggregation control information, and the processormay control the radio communication module so that feedback informationindicating the determined reception error status when receiving thecarrier aggregation control information can be transmitted to the basestation.

Furthermore, the processor may decide the available carrier based uponthe carrier aggregation control information, after a predeterminednumber of sub-frames, starting from a time point when the carrieraggregation control information is received.

Effects of the Invention

According to the exemplary embodiments of the present invention, thepresent invention has the following effects.

First of all, by using the exemplary embodiments of the presentinvention, efficient communication may be performed.

Secondly, in a multi-carrier environment, diverse control information ofan LTE system may be effectively transmitted and received.

Thirdly, since available carriers of a user equipment aresemi-statically and/or dynamically assigned, whenever required, by usinga lower-layer signaling method according to the present invention, radioresources may be efficiently managed.

The effects that may be gained from the embodiment of the presentinvention will not be limited only to the effects described above.Accordingly, additional effects of the present application will be setforth in part in the description which follows and in part will becomeapparent to those having ordinary skill in the art upon examination ofthe following or may be learned from practice of the presentapplication. More specifically, unintended effects obtained upon thepractice of the present invention may also be derived by anyone havingordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

(a) and (b) of FIG. 1 illustrate a method for transmitting and receivingmultiple bandwidth radio frequency (RF) based signals.

FIG. 2 illustrates an exemplary method for allocating a frequency in amulti-carrier system.

FIG. 3 illustrates a method for transmitting physical channels used in a3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution)system and a method for transmitting general signals by using suchphysical channels.

FIG. 4 illustrates a format according to which a synchronization channeland a primary broadcast channel are transmitted for each carrier thatcan be applied to the exemplary embodiments of the present invention.

FIG. 5 illustrates a method of determining a carrier for a specific userequipment regardless of the carrier settings of a cell, by using userequipment specific carrier assignment information according to anexemplary embodiment of the present invention.

FIG. 6 illustrates an exemplary process, wherein the base stationassigns a carrier to the user equipment and controls the assignedcarrier according to an exemplary embodiment of the present invention.

FIG. 7 illustrates exemplary carrier sleep/awake operations according toan exemplary embodiment of the present invention.

FIG. 8 illustrates a block view showing exemplary structures of atransmitting end and a receiving end according to another exemplaryembodiment of the present invention.

BEST MODE FOR CARRYING OUT THE PRESENT INVENTION

Hereinafter, the preferred embodiments of the present invention will nowbe described in detail with reference to the accompanying drawings. Thedetailed description of the present invention that is to be disclosedalong with the appended drawings is merely given to provide to describethe exemplary embodiment of the present invention. In other words, theembodiments presented in this specification do not correspond to theonly embodiments that can be realized according to the presentinvention. In the following description of the present invention, thedescription of detailed features of the present invention will be givenin order to provide a full and complete understanding of the presentinvention. However, it will be apparent to those skilled in the art thatthe present invention can be realized even without the detailed featuresdescribed herein. For example, the present invention will be describedin detail as follows based upon an assumption that the mobilecommunication system used in the present invention corresponds to a 3GPPLTE system. However, with the exception for the unique features of the3GPP LTE system, other mobile communication systems may also be randomlyapplied in the present invention.

In some cases, in order to avoid any ambiguity in the concept (or idea)of the present invention, some of the structures and devices disclosed(or mentioned) in the present invention may be omitted from theaccompanying drawings of the present invention, or the present inventionmay be illustrated in the form of a block view focusing only on theessential features or functions of each structure and device.Furthermore, throughout the entire description of the present invention,the same reference numerals will be used for the same elements of thepresent invention.

Furthermore, in the following description of the present invention, itwill be assumed that the term user equipment is used to collectivelyrefer to a mobile or fixed user-end device, such as a UE (UserEquipment), an MS (Mobile Station), and so on. Additionally, it willalso be assumed that the term base station is used to collectively referto a random node of a network end communicating with the user equipment,such as Node B, eNode B, Base Station, and so on.

In the exemplary embodiments of the present invention, the medium accesscontrol layer may be used as a term collectively referring to a layerhaving a higher concept than that of the PHY (Physical layer or layer 1)in an OSI 7 layer. Additionally, in the drawings, which are appended todescribe the exemplary embodiments of the present invention, thefrequency carriers are illustrated to be contiguous to one another.However, as described above, the frequency carriers may not bephysically contiguous to one another.

The wireless environment considered in the present invention includesall environments for the general multi-carrier support. Morespecifically, in the present invention, a multi-carrier system or acarrier aggregation system refers to a system that aggregates one ormore carriers, each having a bandwidth smaller than the targeted band,when a wideband is targeted in order to support wideband. Whenaggregating at least one or more carriers each having a bandwidthsmaller than the targeted band, the bandwidth of the aggregated carriersmay be limited to a bandwidth that is used in a conventional system inorder to satisfy backward compatibility with the conventional IMTsystem. For example, the conventional 3GPP LTE system supports thebandwidths of {1.4, 3, 5, 10, 15, 20} MHz, and, in the LTE_A system,only the above-mentioned bandwidths, which are supported by LTE, areaggregated so that the LTE-A system can support a bandwidth larger than20 MHz. Furthermore, regardless of the bandwidth used in theconventional system, a new bandwidth may be defined so that the newlydefined bandwidth can support carrier aggregation.

Also, in the present invention, carrier aggregation corresponds to aconcept including contiguous carrier aggregation, wherein only thecontiguous carriers are aggregated, and non-contiguous carrieraggregation or spectrum aggregation, wherein non-contiguous carriers mayalso be aggregated. Furthermore, the term bandwidth aggregation (BWaggregation) may be alternately used with the term carrier aggregation.

The method for transmitting and receiving control information accordingto the present invention assumes a situation after a radio resourcecontrol (RRC) connection is established between the user equipment andthe base station via initial access. Accordingly, a method forprocessing a random access procedure, which can be applied to theexemplary embodiments of the present invention, will first be describedin detail.

Method for Processing a Random Access Procedure

FIG. 3 illustrates a method for transmitting physical channels used in a3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution)system and a method for transmitting general signals by using suchphysical channels.

In step S301, the user equipment performs initial cell search such assynchronization with the base station, when it newly enters a cell orwhen the power is turned on. In order to do so, the user equipmentsynchronizes with the base station by receiving a PrimarySynchronization Channel (P-SCH) and a Secondary Synchronization Channel(S-SCH) from the base station, and then acquires information such ascell ID, and so on. Thereafter, the user equipment may acquire broadcastinformation within the cell by receiving a Physical Broadcast Channelfrom the base station. Meanwhile, in the step of initial cell search,the user equipment may receive a Downlink Reference Signal (DL RS) so asto verify the downlink channel status.

Once the user equipment has completed the initial cell search, in stepS302, the corresponding user equipment may acquire more detailed systeminformation by receiving a Physical Downlink Shared Channel (PDSCH)based upon the Physical Downlink Control Channel (PDCCH) and thePhysical Downlink Control Channel information.

Meanwhile, if the user equipment initially accesses the base station, orif there are no radio resources for signal transmission, the userequipment may perform a Random Access Procedure (RACH), as shown in stepS303 to step S306, with respect to the base station. In order to do so,the user equipment may transmit a specific sequence to a preamblethrough a Physical Random Access Channel (PRACH) (S303), and may receivea response message respective to the random access through the PDCCH andthe PDSCH corresponding to the PDCCH (S304). In case of a contentionbased random access, excluding the case of a handover, a ContentionResolution Procedure may be additionally performed afterwards, such asan additional transmission of a physical random access channel (S305)and reception (S306).

After performing the above-described process steps, the user equipmentmay perform PDCCH/PDSCH reception (S307) and Physical Uplink SharedChannel (PUSCH)/Physical Uplink Control Channel (PUCCH) transmission(S303), as general uplink/downlink signal transmission procedures.Meanwhile, the control information, which is transmitted by the userequipment to the base station or received by the user equipment from thebase station via uplink, includes downlink/uplink ACK/NACK signals, CQI(Channel Quality Indicator)/PMI (Precoding Matrix Index)/RI (RankIndicator), and so on. In case of the 3GPP LTE system, the userequipment may transmit control information, such as the above-describedCQI/PMI/RI through the PUSCH and/or the PUCCH.

Based upon the above-mentioned description, a Random Access procedureprovided by the LTE system will hereinafter be briefly described.

First of all, the user equipment performs the Random Access procedure inthe cases listed below:

-   -   when a Radio Resource Control (RRC Connection) between the user        equipment and the base station does not exist, and, therefore,        when the user equipment performs initial access    -   when the user equipment first accesses a target cell, during a        handover process    -   when a random access procedure is requested by a command made by        the base station    -   when data that are to be transmitted via uplink occur, in a        situation wherein time synchronization of the uplink does not        match, or wherein a designated radio resource, which is used for        requesting radio resource, does not exist    -   when a recovery process is performed during a radio link failure        or a handover failure.

During a process of selecting a random access preamble, the LTE systemprovides both contention based random access procedure, wherein the userequipment randomly selects a single preamble from a specific group anduses the selected preamble, and non-contention based random accessprocedure, wherein a specific user equipment uses a random accesspreamble, which is assigned only to the specific user equipment by thebase station. Herein, however, the usage of the non-contention basedrandom access procedure may be limited only during the above-describedhandover process, or when requested by a command made by the basestation.

Meanwhile, a process during which the user equipment performs a randomaccess with a specific base station may broadly include (1) a step ofhaving the user equipment transmit a random access preamble to the basestation (if there is no confusion, hereinafter referred to as a step oftransmitting “message 1”), (2) a step of receiving a random accessresponse from the base station with respect to the transmitted randomaccess preamble (if there is no confusion, hereinafter referred to as astep of receiving “message 2”), (3) a step of transmitting an uplinkmessage by using information received from the random access responsemessage (if there is no confusion, hereinafter referred to as a step oftransmitting “message 3”), and (4) a step of receiving a messagerespective to the uplink message from the base station (if there is noconfusion, hereinafter referred to as a step of receiving “message 4”).

When considering the multi-carrier environment, it may be difficult todirectly apply the random access procedure, which is described abovewith reference to FIG. 3, without any modification. Therefore, aninitial access method based upon the multi-carrier environment in moredetail will hereinafter be described.

An assumption made prior to performing the random access method in themulti-carrier environment will first be described.

FIG. 4 illustrates a format according to which a synchronization channeland a primary broadcast channel are transmitted for each carrier thatcan be applied to the exemplary embodiments of the present invention.

The initial access method proposed in the exemplary embodiments of thepresent invention will hereinafter be described under the assumptionthat a synchronization channel signal and a primary broadcast channel(PBCH) exist in all downlink (DL) component carriers, as shown in FIG.4. Also, in this exemplary embodiment of the present invention, it willbe essentially assumed that a physical cell identifier (PCI), which isknown through the synchronization channel, and which is beingtransmitted from each downlink component carrier, is identical for allmulti-carriers within a single cell.

Hereinafter, an example of a random access method in the multi-carrierenvironment according to the present invention will now be described indetail.

During an Initial cell search process, the user equipment attempts toperform a synchronization channel signal search in frequency rasterunits.

When the user equipment successfully performs the synchronizationchannel signal search from any one of the aggregated downlink carriers,the corresponding carrier may be determined as a downlink (DL) referencecarrier. During this process, the physical cell identifier is received.Even if the corresponding carrier is not separately set up as thereference carrier, the downlink carrier from which the synchronizationchannel signal is searched will hereinafter be referred to as thereference carrier for simplicity.

The primary broadcast channel is received from the reference carrier sothat information such as a downlink transmission bandwidth, a PhysicalHybrid ARQ Indicator Channel (PHICH), a system frame number (SFN), anumber of transmission antennae in a base station, and so on.

In order to receive information required for performing the initialaccess, the user equipment receives system information (SI-x), which istransmitted to the reference carrier. Herein, an uplink bandwidth, anuplink E-UTRA absolute radio frequency channel number (UL EARFCN),higher-layer signaling associated with diverse uplink/downlink channelsettings, and so on, may be transmitted to the system information. Morespecifically, when the absolute radio frequency channel number andbandwidth of the uplink carrier is known after receiving the systeminformation, information on an uplink-downlink pair band is receivedfrom the frequency division multiplexing process.

The user equipment may set up the uplink carrier, from which theabove-described information is received by using the above-describedmethod, as the uplink reference carrier. As described above, in thedescription of the present invention, even if a reference carrier is notseparately set up in the uplink, the uplink carrier, which is linked tothe downlink carrier from which the synchronization channel signal issearched, will hereinafter be referred to as the reference carrier forsimplicity.

The base station transmits cell-specific multi-carrier set-upinformation through the downlink reference carrier, so as to notify theuser equipment that the carrier settings have been made in thecorresponding cell. During this process, the same physical cellidentifier may be transmitted, or different physical cell identifiersmay be transmitted for each carrier, through the synchronization signalof the aggregated multiple downlink carriers within a single cell. Whenthe user equipment is informed of the carrier set-up information of thecorresponding cell, the carrier may be changed by performing a simplehandover process.

The cell-specific multi-carrier set-up information may be transmittedthrough extended system information (extended SI-x), which is designatedto user equipments of the LTE-A standard, or the cell-specificmulti-carrier set-up information may be transmitted to the userequipment through a reserved portion of the primary broadcast channel(PBCH) regulated by the general LTE standard (LTE Rel. 8). As anothertransmission method, the cell-specific multi-carrier set-up informationmay be included in the broadcast information, the system information, orthe absolute radio frequency channel number of the corresponding cell.

Such cell-specific multi-carrier set-up information may includeinformation indicating a downlink carrier among the multi-carriersincluded in the corresponding cell, carrier frequency information,downlink/uplink carrier link information of the corresponding cell, andso on.

If the physical cell identifier values for each of the multiple downlinkcarriers within the same cell are equal to one another, downlink carrierinformation within the cell, which is received (or acquired) from thecell-specific multi-carrier set-up information, may be used. Therefore,the user equipment may not be required to receive the primary broadcastchannel, system information, and synchronization channel of anotherdownlink carrier.

Conversely, the physical cell identifier values for each of the multipledownlink carriers within the same cell are different from one another,the user equipment uses the downlink carrier information received (oracquired) from the cell-specific multi-carrier set-up information, so asto perform a synchronization channel search process in each of thedownlink carriers, thereby receiving the physical cell identifiers foreach carrier. The user equipment may use the received physical cellidentifier when performing reference signal sequence generation,scrambling, and so on, for each carrier. Thereafter, the user equipmentreceives the primary broadcast channel and system information, and theuser equipment may then be capable of knowing information on the uplinkcarriers, which are connected (or linked) to each downlink carrier.

When link information of the downlink/uplink carriers within thecorresponding cell is separately transmitted, the user equipment may beinformed of the link information without receiving the systeminformation.

Subsequently, the user equipment uses the physical random access channelparameter, which is transmitted through the reference downlink carrier,so as to transmit a random access preamble (i.e., message 1) to the basestation through the physical random access channel of the referenceuplink carrier. When the base station receives the random accesspreamble, the base station transmits a random access channel response(message 2) through the downlink reference carrier.

At this point, the random access channel response, which is transmittedfrom the base station to the user equipment, may be transmitted from thebase station by broadly using two different methods, which will bedescribed below.

A first method for transmitting a random access channel responsecorresponds to a method of transmitting the random access channelresponse through all downlink component carriers that are linked to theuplink carrier, to which the random access preamble is transmitted. Asecond method for transmitting a random access channel responsecorresponds to a method of transmitting the random access channelresponse through only one of the downlink component carriers that arelinked to the uplink carrier, to which the random access preamble istransmitted.

With the exception for the portion related to the multi-carriers, theother message 1 to message 3 are similar to those described withreference to FIG. 3. Therefore, the detailed description of the samewill be omitted for simplicity of the description of the presentinvention.

The detailed description of the random access methods in a multi-carrierenvironment that can be applied to the exemplary embodiments of thepresent invention are as described above. However, the above-describedrandom access methods are merely exemplary. And, therefore, it will beassumed that the exemplary embodiments of the present invention areapplied, after the RRC connection between the user equipment and thebase station is established, in a multi-carrier environment, regardlessof the detailed configuration of the random access procedure.

Transmission of Control Information Related to Carrier Assignment

Hereinafter, a method for assigning carriers as control information thatmay be transmitted from the base station to the user equipment, after aradio resource control (RRC) connection is established, according to anexemplary embodiment of the present invention will be described indetail.

When the user equipment transmits message 3 to the base station, theuser equipment and the base station may perform an agreement procedurein accordance with the performance (or ability) of the user equipment.Accordingly, the base station may allocate user equipment (UE)-specificcarrier assignment information or UE-group-specific carrier assignmentinformation or UE-specific carrier assignment information within a basestation region (or cell-specific carrier assignment information) to theuser equipment (UE).

Hereinafter, UE-specific or UE-group-specific or cell-specific carrierassignment will be collectively referred to as ‘UE-specific carrierassignment’, and, herein, ‘UE-specific carrier assignment information’may include information on an available candidate carrier enabling aspecific user equipment to transmit/receive control information/datafrom a cell. A downlink or uplink available candidate carrier or anactivated carrier among the available candidate carriers may refer to anobject carrier, wherein data scheduling through the correspondingcarrier may be realized at any time point, and wherein schedulingcontrol information of the user equipment respective to theabove-mentioned data scheduling may be monitored.

Even though carrier settings of a cell are set-up to be symmetrical(i.e., when a number of uplink component carriers is equal to a numberof downlink component carriers), when downlink-uplink (DL-UL) linkageinformation of the system is required to be ignored (overridden), inorder to support user equipments using asymmetrical carrier aggregationwithin the corresponding cell, such UE-specific carrier assignmentinformation may correspond to a method for performing such functions.This will be described in more detail with reference to FIG. 5.

FIG. 5 illustrates a method of determining a carrier for a specific userequipment regardless of the carrier settings of a cell, by usingUE-specific carrier assignment information according to an exemplaryembodiment of the present invention.

The UE-specific carrier assignment information may be transmitted onlywith respect to a user equipment or a user equipment group that shouldoverride the downlink-uplink linkage information of the system, or theUE-specific carrier assignment information may be transmitted to alluser equipments using carrier aggregation. As shown in FIG. 5, 2downlink component carriers and 2 uplink component carriers exist as theavailable candidate carriers, and, the carriers are aggregated in asymmetrical multi carrier aggregation, by performing an override, thesymmetrical multi carrier aggregation format is modified to anasymmetrical multi carrier aggregation, wherein two downlink componentcarriers are connected to a single uplink component carrier #0.

In the above-described case, the user equipment performs blind decodingon a physical downlink control channel (PDCCH) from a candidate downlinkcomponent carrier, which may be used by the corresponding userequipment. Accordingly, if a physical downlink control channel is notdetected, the user equipment may not receive the data respective to thecorresponding carrier within the corresponding sub-frame.

Hereinafter, an exemplary carrier assignment method according to thepresent invention will be briefly described with reference to FIG. 6.

FIG. 6 illustrates an exemplary process, wherein the base stationassigns a carrier to the user equipment and controls the assignedcarrier according to an exemplary embodiment of the present invention.

Referring to FIG. 6, by performing the above-described random accessprocedure, a radio resource control (RRC) connection between the userequipment and the base station may be established (S601).

Accordingly, the base station may transmit UE-specific orUE-group-specific carrier assignment information (S602).

At this point, it is preferable that the format according to which thecarrier assignment information is delivered corresponds to higher-layercontrol signaling, e.g., radio resource control signaling. Since theformat of carrier set-up information and information included in thecarrier set-up information are identical to those described above,description for the like parts will be omitted for simplicity, anddetailed description of the above-mentioned information will hereinafterbe additionally provided.

The user equipment is assigned with one or more uplink/downlink carriersbased upon the carrier assignment information from the base station,and, then, by using the assigned carriers, data exchange may beperformed between the user equipment and the base station may beperformed (S603).

Thereafter, based upon a predetermined cycle period, or wheneverrequired, the base station may semi-dynamically transmit lower-layercarrier aggregation control information to the user equipment by usingan event trigger method (S604).

Herein, the lower-layer carrier aggregation control information mayrefer to information enabling carrier assignment information, which issemi-statically transmitted to the user equipment, to be overridden, ormay refer to information notifying a specific user equipment or aspecific user equipment group of the carrier aggregation situation. Thiswill also be described in more detail in the following description.

Furthermore, a step of setting-up at least one or more UE-specific orUE-group-specific or cell-specific carriers without requesting aseparate set of carrier assignment information, and a step oftransmitting set-up information on an available candidate carrier and/orcarrier status change information and/or link change information throughthe at least one or more carriers that are set-up, as described above,as the carrier aggregation control information may also be includedherein.

Based upon whether or not an error occurs during a reception oflower-layer carrier aggregation control information in the base station,the user equipment may optionally transmit feedback informationindicating whether or not a reception error occurs to the base station.

In the carrier assignment process that is briefly described above withreference to FIG. 6, step S602 and step S604 may be semi-statically,dynamically, or semi-dynamically performed multiple times as required.Hereinafter, the carrier assignment information of step S602, thelower-layer carrier aggregation control information of step S604, andthe feedback of S605 will be described in more detail.

The carrier assignment information will first be described in detail.

Transmission Format of Carrier Assignment Information

When the based station according to an exemplary embodiment of thepresent invention transmits the above-described UE-specific carrierassignment information to the user equipment (UE), the UE-specificcarrier assignment information may be used in the following formats.

Since the UE-specific carrier assignment information essentiallycorresponds to information that is not required to be dynamicallymodified, the base station may notify the user equipment of theUE-specific carrier assignment information via UE-specific orcell-specific radio resource control (RRC) signaling, or the basestation may transmit the UE-specific carrier assignment information tothe user equipment by using a separate channel at a specific cycleperiod.

Based upon an operational aspect, such as a traffic situation of theuser equipment or an overall traffic situation within a cell, anavailable carrier of a user equipment may be required to be dynamicallylimited or extended. In order to support such situations:

1) the base station is required to prevent the user equipment frommonitoring the control channel (PDCCH) respective to all downlinkcandidate (available) carriers that are assigned to the correspondingbase station by using the UE-specific carrier assignment information.Therefore, the base station may use a first layer/second layer controlsignaling (e.g., physical downlink control channel) so as toUE-specifically provide information on the downlink component carrierthrough which the corresponding user equipment intends to monitor thecontrol channel.

More specifically, the base station may transmit at least one or more ofthe multiple component carriers, which are supported by thecorresponding base station, as one or more available component carriersof the user equipment via radio resource control signaling. Thereafter,as required, the base station may dynamically control usage status oractivation status (e.g., on/off, awake/sleep, oractivation/deactivation) of each of the one or more component carriersassigned to the user equipment through the first layer/second layercontrol signaling.

2) As another object, in order to dynamically allocate a larger numberof component carriers respective to available downlink or uplinkcomponent carriers of the user equipment, which is set-up viaUE-specific radio resource control signaling, i.e., a number ofcomponent carriers within the range of available carriers assigned viaradio resource signaling or a number of component carrier within otherranges, the base station may UE-specifically, perform first layer/secondlayer control signaling.

For example, the base station may semi-statically allocate only onecarrier respective to each of an uplink and a downlink via radioresource control signaling to the user equipment, or the base stationmay designate a carrier, which is accessed by an initial accessprocedure, as a connection set-up carrier, and, whenever and as required(event-triggered), the base station may dynamically allocate additionalcarriers to the user equipment via first layer/second layer controlsignaling, or the base station may retrieve the assigned carriers.

It will be understood that the above-described radio resource controlsignaling and the first layer/second layer control signaling will becommonly applied to the exemplary embodiments of the present inventionthat will hereinafter be described in detail.

Meanwhile, the base station may prevent information, which is includedin the first layer/second layer control signaling, from including validtiming offset information in the corresponding control signaling andfrom being transmitted for each sub-frame. Accordingly, the downlinkphysical resource may be saved (or reserved).

In conclusion, the UE-specific carrier assignment information may besemi-statically or dynamically (semi-dynamically) transmitted viaUE-specific radio resource control (RRC) signaling at a predeterminedcycle period (cycle period ≧1TTI), or may be transmitted by using anevent-triggered method. Herein, a method of transmitting the UE-specificcarrier assignment information to the user equipment by using both ofthe above-described transmission methods may also be included.

As a detailed example of a method for transmitting control informationrelated to carrier assignment according to the present invention, thebasic UE-specific carrier assignment information uses UE-specific RRCsignaling, and lower layer (L1/L2) control signaling may be used withrespect to change in the UE-specific carrier assignment that occursnon-specifically. Herein, an example of the change in the UE-specificcarrier assignment that occurs non-specifically may include an on/offstatus (status indicating whether or not control channel monitoring ofthe user equipment is performed) on at least one of the uplink/downlinkcomponent carriers assigned to the user equipment. Such lower layercontrol signaling may be dynamically or semi-dynamically transmitted ata predetermined cycle period (cycle period ≧1TTI), or may be transmittedby using an event-triggered method.

Meanwhile, in order to notify the user equipment of the UE-specificcarrier assignment information, the base station may use the followingmethods.

1) The user equipment essentially follows the carrier aggregationconfiguration of a cell. However, when a change is required to be made,a method of transmitting only the information, which is configured tooverride the carrier aggregation configuration of a cell, may be used.For example, although the carrier aggregation configuration of a cell issymmetrical, in case of a specific LTE-A user equipment, an asymmetricalcarrier aggregation capability may be used. In this case, the basestation may transmit link information to the user equipment, wherein thelink information may override the carrier configuration of thecorresponding cell (linkage information of a DL-UL carrier, which isreceived through the system information within the corresponding cell).

2) The base station may transmit information, such as downlink (DL)carrier index or extended downlink E-UTRAN absolute radio frequencychannel number (extended DL EARFCN), to the user equipment, therebytransmitting only information on a downlink carrier frequency number. Inthis case, the user equipment may be capable of receiving uplink (UL)linkage information through system information (SI-x) of thecorresponding carrier. In other words, when the base station firstnotifies an index or frequency number of a downlink carrier to the userequipment, the user equipment may be informed of the information on theuplink carrier, which is connected to the corresponding downlinkcarrier, through the system information.

3) Herein, a method wherein the base station provides the user equipmentwith uplink (UL) linkage information, which is connected to thecorresponding downlink carrier, along with the assigned downlink carrierinformation.

Lower Layer Carrier Aggregation Control Information

As described above, the base station may dynamically control thecarrier, which the base station semi-statically assigned to the userequipment, by using higher layer signaling (e.g., radio resource controlsignaling), or the base station may use lower layer carrier aggregationcontrol information (e.g., L1/L2 control signaling) in order to overridethe uplink/downlink carrier configuration information of a cell. Inother words, the lower layer carrier aggregation control informationaccording to the present invention refers to information that enablesthe base station to override the UE-specific carrier assignmentinformation, which is semi-statically transmitted to the user equipment,or refers to information that notifies a carrier aggregation situationto a specific user equipment or user equipment group.

In the description of the present invention, such lower layer carrieraggregation control information will hereinafter be referred to as firstlayer carrier aggregation control information (or L1 CA) for simplicity.Herein, the L1 CA control information may be transmitted from the basestation to the user equipment at a predetermined cycle period, and whenrequired, the L1 CA control information may also be dynamicallytransmitted to the user equipment by using the event-triggered method.

The L1 CA control information will now be described in detail.

When the L1 CA control information is used as information notifying theabove-described carrier aggregation situation, and when UE-specific orUE-group-specific carrier assignment is configured by using theconventional UE-specific radio resource control signaling method, thecarrier aggregation situation may correspond to a change in informationon an increase or decrease in a number of carriers and/or a change inactivation/deactivation status information of a configured carrier orall available carriers and/or a change in carrier index information inan increased or decreased situation and/or a change in uplink/downlinkcarrier connection information associated to the carrier indexinformation. In this case, the significance of the number of carriersmay correspond to information on candidate carrier configuration,through which the user equipment may receive a data shared channel(SCH), and the significance of the number of carriers may alsocorrespond to information on a direct configuration of a carrier,through which the data shared channel can be transmitted.

As an exemplary format of the candidate carrier configuration,information on a number of carriers and/or a carrier index and/orassociated linkage information may correspond to information indicatinga carrier situation in which the user equipment is required to perform aminimum blind decoding process on the physical downlink control channel.Conversely, such information may also correspond to informationindicating a candidate carrier situation in which the user equipment isrequired to perform a maximum blind decoding process on the physicaldownlink control channel.

Meanwhile, when the L1 CA control information directly indicates acarrier through which an uplink/downlink data shared channel istransmitted/received, and, as an uplink/downlink control informationcorresponding to the L1 CA control information, a carrier indicatorindicating a carrier through which the corresponding physical downlinkshared channel or physical uplink shared channel is transmitted, may beadditionally included, thereby being signaled in the form of a physicaldownlink control channel. More specifically, the L1 CA controlinformation may be transmitted over a physical downlink control channeldownlink control information format respective to the correspondingphysical downlink shared channel or physical uplink shared channel alongwith the downlink channel allocation control information.

At this point, a number of bits used in an L1 CA control informationfield, which corresponds to the carrier indicator, may be defined as anumber of bits having the value of

┌log₂Z┐

based upon a number of available carriers “Z” that are semi-staticallyassigned, wherein this information corresponds to UE-specific carrierconfiguration information. In another method for defining the number ofbits, the number of bits may be defined by using the above-describedmethod for calculating the number of bits, based upon a number of allavailable uplink/downlink component carriers, or based upon a number ofcases using a randomly limited number of component carrier aggregations.In yet another method, the number of bits may be defined as a fixednumber of bits configured to indicate an indication information formatrespective to whether or not a physical downlink shared channel within acarrier is transmitted, the carrier being identical to the downlinkcomponent carrier through which the corresponding physical downlinkcontrol channel is transmitted, or whether or not a physical uplinkshared channel within an uplink component carrier, which is connected tothe transmission status of the physical downlink shared channel.Additionally, when required, link configuration information betweencarriers, through which data are transmitted (e.g., link informationbetween uplink and downlink carriers), may be signaled along with thenumber of bits.

The above-described configuration and attributes of the L1 CA controlinformation may be identically applied when realizing carrierconfiguration by using the UE-specific radio resource control signaling.

Application Point of L1 CA Control Information

When transmitting the L1 CA control information to the user equipmentfrom a random sub-frame, and in case a separate verification (orconfirmation) procedure (e.g., feedback) is not required, the userequipment or cell/base station may apply the corresponding carrieraggregation status starting from a downlink or uplink sub-frame after p(p≧0) number of sub-frames from the corresponding sub-frame. When apredetermined verification procedure is required to be performed, thecorresponding carrier aggregation status may be applied starting from adownlink or uplink sub-frame after q (q≧0) number of sub-framesimmediately after the point when the user equipment or cell/base stationhas transmitted a verification message respective to a successful L1 CAcontrol information reception.

As described above in the description of the present invention, the L1CA control information may correspond to information indicating aUE-specific carrier aggregation status. However, the L1 CA controlinformation may also correspond to information indicatingUE-group-specific, cell-specific, base station-specific,cluster-specific, or system-specific carrier aggregation status.

Transmission Cycle Period of LA CA Control Information for DynamicCarrier Management

1) Dynamic Transmission

The L1 CA control information may be transmitted for each sub-frame.

And, in this case, even if a verification procedure (such as ACKresponse/NACK response) on the L1 CA control information is not requiredor performed, a level of influence caused by the error propagation isextremely low. More specifically, in a random sub-frame, even if anerror occurs during the reception of the L1 CA control information,since a new set of L1 CA control information is transmitted in the nextsub-frame, the error respective to the L1 CA control information may belimited to the corresponding sub-frame.

2) Semi-Dynamic Transmission

A method of transmitting the L1 CA control information at a cycle periodof more than 1 sub-frame and using previously transmitted L1 CA controlinformation during the corresponding cycle period may be applied herein.In this case, since the L1 CA control information is not transmitted foreach sub-frame, a waste in resource (overhead) may be reduced. However,once the L1 CA control information is broken, the respective error mayinfluence the sub-frame for as long as the transmission cycle period.

At this point, when the L1 CA control information is semi-staticallytransmitted, in order to verify whether or not an error occurs duringthe reception of the L1 CA control information, the user equipment maytransmit an ACK/NACK corresponding to whether or not a reception erroroccurs during the reception of the L1 CA control information. In orderto do so, the user equipment receiving the L1 CA control information maydetermine a presence or absence of the reception error with respect tothe received L1 CA control information by using a method such as acyclic redundancy check (CRC) process. Based upon the result fordetermining the presence or absence of the reception error, if thesub-frame that has received the L1 CA control information corresponds toan n^(th) sub-frame, the user equipment may transmit a feedback to ann+k^(th) (k≧1) sub-frame, wherein the feedback notifies the base stationof the presence or absence of the reception error. In the form of afeedback, the user equipment may use a physical uplink control channelformat 1 (PUCCH format 1) of LTE Release 8 (LTE Rel. 8). At this point,in order to provide additional error-resistance, the base station maytransmit multiple sets of ACK information or ACK/NACK informationthrough one or more uplink sub-frames. And, as another method, the basestation may direct (or request) a verification on a reception status tothe user equipment. Furthermore, such feedback may also have the formatof CRC protection ACK or ACK/NACK.

3) Event-Triggered Transmission

Unlike the above-described cases, as a method that does not configure aseparate cycle period, an event-triggering method may be used. Morespecifically, when it is determined to be required by the system orcell/base station, the L1 CA control information is transmitted as arandom time point through one or more sub-frames. At this point,multiple sub-frames may also be used. The purpose of using multiplesub-frames is to performed iterated (or repeated) transmission in orderto enhance the reliability of the control information included in themultiple sub-frames. Herein, the multiple sub-frames may correspond tocontiguous sub-frames, the multiple sub-frames may correspond tonon-contiguous sub-frames. Moreover, in the L1 CA control informationtransmission performed by a cell/base station, with respect to when themethod proposed in the above description is applied, the user equipmentreceiving the last sub-frame, which transmits the corresponding L1 CAcontrol information, may transmit feedback information, which indicatesthe presence or absence of an error when receiving the last sub-frame,to the base station.

Meanwhile, there may occur a case when the user equipment is unaware ofa sub-frame timing according to which the cell/base station transmitsthe L1 CA control information. In this case, a method for adequatelydetermining whether or not the L1 CA control information has beentransmitted or whether or not an error has occurred during the receptionof the transmitted L1 CA control information may be used, and the methodwill now be described in detail.

A position within a physical/logical resource of a physical channel towhich the L1 CA control information is being transmitted may be uniquelyconfigured. More specifically, by using a method of limiting a resourcearea to which the L1 CA control information is transmitted in advance,and of performing a CRC-masking process by using a specific Cell RadioNetwork Temporary Identifier (C-RNTI), the L1 CA control information maybe UE-specifically transmitted. Accordingly, the user equipment mayperform decoding with respect to a candidate resource of a physicalchannel, to which the L1 CA control information is transmitted, withinall of the sub-frames. Based upon the decoded result, when the decodingprocess is successfully performed, the user equipment transmits an ACKfeedback to the cell/base station. And, if the decoding process fails tobe performed successfully, instead of transmitting a NACK feedback tothe cell/base station, the user equipment does not perform anysubsequent operations. Accordingly, by using this method, the userequipment may perform the verification procedure.

At this point, when the sub-frame receiving the L1 CA controlinformation corresponds to the n^(th) sub-frame, the user equipment maytransmit feedback information to the n+k^(th) (k≧1) sub-frame viauplink. In the form of a feedback, the user equipment may use a physicaluplink control channel format 1 (PUCCH format 1) of LTE Release 8 (LTERel. 8). At this point, in order to provide additional error-resistance,the base station may transmit multiple sets of ACK information orACK/NACK information through one or more uplink sub-frames. And, asanother method, the base station may direct (or request) a verificationon a reception status to the user equipment. Furthermore, such feedbackmay also have the format of CRC protection ACK or ACK/NACK.

Method for Transmitting L1 CA Control Information

Hereinafter, a detailed format of transmitting the L1 CA controlinformation will be described in detail.

Since the L1 CA control information corresponds to information on themanagement of a carrier, which is to receive control information and/ordata, it may be preferable to have the L1 CA control information betransmitted in a physical downlink control channel region. In this case,also, it may be preferable to perform a verification procedure on thetransmission of the physical downlink control channel or a physicaldownlink control channel map by using a first layer (L1) or aCRC-protected feedback.

1) Method for Transmitting L1 CA Control Information by Using aDedicated Channel

First of all, just as the transmission of a Physical Control FormatIndicator Channel (PCFICH) of the LTE Release 8 (LTE Rel-8), a method oftransmitting the L1 CA control information by using a separate channelother than the physical downlink control channel is proposed herein. Inthis case, the L1 CA control information may be transmitted by using aformat of n number of control channel elements (nCCE: n Control ChannelElements, n>0) after a physical downlink control channel region, whichis defined by the LTE standard.

2) Method for Transmitting L1 CA Control Information by Applying an LTERel-8 Standard Physical Downlink Control Channel Transmission Scheme toa Physical Downlink Control Channel Region

This method proposes that the L1 CA control information maintains theformat of n number of control channel elements (nCCE) and this methodalso proposes that the location, to which the L1 CA control informationis transmitted, is limited to a location being included in a commonsearch place. In this case, since the size of the common shared place islimited, it may be preferable to additionally apply a method ofUE-specifically limiting the search space. More specifically, thetransmission location of the L1 CA control information may be limited tospecific locations, such as a very first (or beginning) portion of theUE-specific search place or a very last (or end) portion of theUE-specific search place. At this point, as described above, thetransmission of the L1 CA control information may be performed in a waythat the L1 CA control information transmission does not influence thetransmission of the physical downlink control channel of theconventional LTE Rel-8 or LTE Rel. 9 user equipments.

Meanwhile, in the perspective of a carrier, and not in the perspectiveof a resource area, the L1 CA control information may only betransmitted by a limited Z(≧1) number of downlink carriers. For example,the L1 CA control information may only be transmitted through one ormore primary carriers being user-equipment (UE)-specifically orUE-group-specifically configured. In another example, L1 CA controlinformation may only be transmitted through one or morecell-specifically, base station-specifically, cluster-specifically, orsystem-specifically configured primary carriers, or through one or morebackward compatible carriers or one or more LTE-A only carriers.

3) Method for Transmitting L1 CA Control Information by Adding the L1 CAControl Information to a Downlink Control Information (DCI) Formatwithout Creating a Separate Channel

This method proposes that the L1 CA control information may be includedin a downlink channel assignment (or allocation) DCI format or an uplink(UL) grant DCI format, each format being designed for an LTE-A userequipment. Since this method does not influence the downlink controlinformation format of the LTE user equipment, no error occurs in thebackward compatibility. Also, according to this method, the base stationmay notify the L1 CA control information to the user equipment within aphysical downlink control channel (PDCCH) error range. And, even if anerror occurs during the reception process of the user equipment, sincethe physical downlink control channel itself is dynamic, this method maybe advantageous in that no large problem occurs in the errorpropagation.

Meanwhile, in this method also, in the perspective of a carrier, and notin the perspective of a resource area, the L1 CA control information mayonly be transmitted by a limited Z(≧1) number of downlink carriers. Forexample, the L1 CA control information may only be transmitted throughone or more primary carriers being user-equipment (UE)-specifically orUE-group-specifically configured. In another example, L1 CA controlinformation may only be transmitted through one or morecell-specifically, base station-specifically, cluster-specifically, orsystem-specifically configured primary carriers, or through one or morebackward compatible carriers or one or more LTE-A only carriers.

The following description corresponds to a recapitulation of theabove-described methods for transmitting the L1 CA control information.With respect to each of the three proposed methods, when the L1 CAcontrol information is transmitted within a physical downlink controlchannel area as the physical downlink control channel, which is definedto be used for general purposes based upon the LTE or LTE-A standardusing a general technique, it is described in the description of thepresent invention that the L1 CA control information corresponds toinformation indicating a UE-specific carrier aggregation situation.However, the present invention will not be limited only to this, and theL1 CA control information may also be used as information indicating theuser-equipment (UE)-specific, UE-group-specific, cell-specific, basestation-specific, cluster-specific, or system-specific carrieraggregation situation.

Also, as described above, the L1 CA control information may correspondto a series of carrier indicator information directly configuring ordesignating a random component carrier, through which a random physicaluplink/downlink shared channel, among multiple uplink/downlink componentcarriers, which are assigned to the corresponding user equipment byusing UE-specific (or UE-group-specific) carrier assignment information.In this case, a physical downlink control channel may be configured byencoding the L1 CA control information according to a separate codingformat in a separate L1 CA control information entity unit, within asub-frame, wherein random L1 CA control information is beingtransmitted. Alternatively, a physical downlink control channel may alsobe configured by using a joint coding method, wherein one or more L1 CAcontrol information entities are grouped so as to be encoded.

For example, when the L1 CA control information is UE-specificallydefined, and when the L1 CA control information of several userequipments are transmitted within the same sub-frame, the L1 CA controlinformation may be configured individually for each of the userequipments. In order to do so, the L1 CA control information respectiveto each user equipment may be processed with CRC-masking by using aspecific Cell Radio Network Temporary Identifier (C-RNTI), which may beidentified in UE units, thereby being transmitted. Alternatively, the L1CA control information entities of each user equipment may be encoded byusing the joint coding method, so as to be transmitted through a singlephysical downlink control channel. In this case, the joint-coded L1 CAcontrol information may be processed with CRC-masking by using aspecific Cell Radio Network Temporary Identifier, instead of a generalCell Radio Network Temporary Identifier.

Alternatively, control information having an attribute different fromthat of the L1 CA control information (e.g., carrier indicatorinformation) may also be encoded by using the joint coding method, so asto be transmitted through a single physical downlink control channel.

For example, it will be assumed that the L1 CA control information ofone or more random user equipments corresponds to carrier indicatorinformation, which designates a carrier through which a physicaluplink/downlink shared channel is transmitted, among the UE-specificallyor cell-specifically configured uplink/downlink component carriers.Herein, the L1 CA control information may be joint coded with controlinformation of a downlink control information format, which is relatedto one or more downlink channel allocations, with respect to a downlinkdata shared channel transmission of the same user equipment or of adifferent user equipment, or the L1 CA control information may be jointcoded with control information of a downlink control information format,which is related to one or more sets of uplink grant information, withrespect to an uplink data shared channel transmission of the same userequipment or of a different user equipment.

In this case, joint coding refers to a coding method, wherein a payloadformat is configured by adding the L1 CA control information (e.g.,carrier indicator) to the downlink control information format ofdownlink channel allocation control information or uplink grantinformation control information, and then encoding the configuredpayload format. More specifically, joint coding refers to a codingmethod, wherein the L1 CA control information is added to a conventionaldownlink control information format, and wherein the combined format maybe defined as the random downlink control information format. At thispoint, when different types of control information respective to thesame user equipment are joint coded, the L1 CA control information maybe processed with CRC-masking by using a UE-specific Cell Radio NetworkTemporary Identifier (C-RNTI). And, when different types of controlinformation respective to different user equipments are joint coded, theL1 CA control information may be processed with CRC-masking by using arandom specific Cell Radio Network Temporary Identifier.

In the perspective of transmission timing, when downlink channelallocation information or uplink grant information, respective to adownlink or uplink data shared channel transmission, is joint coded withan L1 CA control information entity, the transmission of a physicaluplink/downlink shared channel respective to the corresponding downlinkchannel allocation information or uplink grant information may beperformed at a sub-frame timing defined by a general LTE or LTE-Astandard, or at such sub-frame timing after a predetermined sub-frameunit offset.

Meanwhile, referring to the methods for transmitting the L1 CA controlinformation proposed in the description of the present invention, thebasic coding method or multiplexing method of the above-described L1 CAcontrol information may also be in a case, wherein the L1 CA controlinformation is transmitted through a separate dedicated physicalchannel, other than the physical downlink control channel, which isdefined for general usage in the general LTE or LTE-A standard, orthrough a physical downlink shared channel.

Additionally, in the methods for transmitting the L1 CA controlinformation proposed in the description of the present invention, thecarrier through which the L1 CA control information is transmitted maycorrespond to all downlink components carriers supported by a cell/basestation, or may correspond to all downlink component carriers beingassigned to the user equipment through UE-specific or UE-group-specificcarrier assignment information, which is configured by using aconventional UE-specific RRC signaling method. Also, the L1 CA controlinformation may be configured to be transmitted only through one or moreUE-specifically, UE-group-specifically, cell-specifically, basestation-specifically, cluster-specifically, or system-specificallyconfigured primary carriers or anchor carriers. Alternatively, the L1 CAcontrol information may also be configured to be transmitted onlythrough a backward compatible carrier or an LTE-A only carrier.

Furthermore, in the methods for transmitting the L1 CA controlinformation proposed in the description of the present invention, acarrier aggregation status, which is indicated by the L1 CA controlinformation after F (F≧0) number of downlink or uplink sub-frames,immediately after the user equipment has received the L1 CA controlinformation, or immediately after the base station has transmitted theL1 CA control information, may be applied to the user equipment and thebase station.

When the L1 CA Control Information is being Transmitted

Hereinafter, exemplary cases that require the L1 CA control informationaccording to the present invention to be transmitted will now bedescribed in detail.

1) When the base station semi-statically assigns a candidate carrier,which is to be used for performing carrier aggregation, to the userequipment by using a method, such as UE-specific radio resource controlsignaling, a case when not all of the carriers assigned to the userequipment are used may dynamically occur. In this case, in order toprevent the user equipment from monitoring the carriers that are notused, the L1 CA control information may be used.

2) When the base station semi-statically assigns a candidate carrier,which is to be used for performing carrier aggregation, to the userequipment by using a method, such as UE-specific radio resource controlsignaling, a situation in which one or more additional carriers arerequired to be additionally assigned (e.g., when information of anunexpectedly high data rate is required to be transmitted), in additionto the carriers already assigned to the user equipment, may occur. Inthis case, the L1 CA control information may be used so that the basestation can allocate additional carriers to the user equipment.

3) In an environment where the number of occurrence of theabove-described situation 1) or situation 2) is extremely low, basicallythe base station transmits information on a candidate carrier to theuser equipment by using UE-specific radio resource control signaling,and the user equipment may perform decoding on the correspondingcarriers. However, in this situation, when an override on the basicallyconfigured carrier assignment is required in a specific situation of thesystem, the base station may limitedly transmit the L1 CA controlinformation to the user equipment. For example, in an event-triggeringmethod, when the L1 CA control information is not required, the basestation may deactivate the L1 CA control information. In anotherexample, the base station may include information on a valid time of theL1 CA control information in the L1 CA control information, the L1 CAcontrol information may be valid only during a specific time period.

4) Regardless of the above-described situations 1) to 3), it will beapparent that the L1 CA control information may be dynamically orsemi-statically transmitted at a predetermined cycle period.

More Detailed Exemplary Embodiment for Applying the L1 CA ControlInformation

Hereinafter, an exemplary embodiment applying the above-described formatand transmission method of the L1 CA control information will now bedescribed in detail. In order to do so, a specific application method ofthe above-described methods proposed in the present invention withrespect to carrier assignment will first be described in detail.Hereinafter, the term ‘carrier assignment information’ collectivelyrefers to the above-described UE-specific carrier assignmentinformation, UE-group-specific carrier assignment information, and otherconcepts similar to the UE-specific carrier assignment information andthe UE-group-specific carrier assignment information.

1. The allocation information of a carrier may be delivered to a radioresource control layer. At this point, the carrier assignmentinformation may be transmitted to the user equipment by usingUE-specific or UE-Group-specific signaling (radio resource control layercontrol signaling or first layer/second layer control signaling).

2. The allocation information of a carrier may be configured of anaggregation with another random set of control information.

3. The usage status (on/off, awake/sleep or activated/deactivated) ofeach carrier, which is assigned to the user equipment via carrierassignment information, may be configured in carrier group units or maybe independently configured for each carrier.

For example, the base station may designate a specific carrier as adownlink (DL) primary carrier and, then, decides an uplink primarycarrier corresponding to the DL primary carrier. Thereafter, thedownlink/uplink primary carriers may be notified to the user equipmentby using the radio resource control signaling method. In this case, thebase station may apply L1 CA control information that can collectivelyturn on/off the uplink/downlink component carriers, which are assignedto the user equipment by using RRC signaling, with the exception for theuplink/downlink primary carriers. At this point, the transmission of theL1 CA control information may be performed by using any one of themethods described in the above-described exemplary embodiments of thepresent invention. Alternatively, the base station may also apply L1 CAcontrol information that can individually control on/off statuses of theuplink/downlink component carriers (having the same meaning as thecarriers used in the description of the present invention), which areassigned to the user equipment by using RRC signaling.

4. The usage status of a specific carrier may be performed (ordetermined) by using a control signaling method on an individualcarrier, such as carrier sleep.

1) A carrier sleep command may be transmitted to a user equipmentthrough a random carrier. However, when the carrier sleep command istransmitted to the user equipment through a downlink carrier, which islinked to a downlink carrier having the carrier sleep command appliedthereto, or which is lined to an uplink carrier having the carrier sleepcommand applied thereto, the individuality of each carrier may beensured and the delivered information size (i.e., overhead) may bedecreased.

2) It may be preferable that the carrier sleep command correspond tocontrol information on an individual single carrier. However, thecarrier sleep may also correspond to control information on a pluralityof carriers. In case of the individual single carrier, the carrier sleepcommand may correspond to a downlink or uplink primary carrier (oranchor carrier). Also, on the contrary, the individual carrier havingthe carrier sleep command applied thereto may also correspond to theremaining carriers excluding the downlink or uplink primary carrier. Atthis point, the corresponding control information on the individualcarrier may be transmitted to a downlink primary carrier.

3) The carrier sleep may be transmitted to the user equipment in animplementation format, wherein the above-described L1 CA controlinformation is imbedded in a physical downlink control channel (PDCCH),in a physical dedicated control channel, or in a control channel havinga DL channel assignment (or allocation)/UL grant information transmittedthereto. Or, the carrier sleep command may be transmitted to aCRC-protected message.

4) The carrier sleep operation may be performed and/or initiated by boththe user equipment/base station.

5) The user equipment does not perform any processing on the carrier,which is in the carrier sleep mode, and when a randomly designated sleepmode period is ended, the corresponding carrier may once again besubject to processing (i.e., return to the normal mode operation). Thesleep mode may also be maintained until the next signaling withouthaving to set up a particular sleep mode period.

6) Herein a carrier awake command may be defined, wherein, when aprimary is configured, among one or more uplink/downlink carriers thatare UE-specifically assigned to a random user equipment, the carrierawake command may generally or individually activate at least some ofthe carriers that operate in the carrier sleep mode, among the remainingcarriers excluding the primary carrier. The methods proposed in thepresent invention as a method for transmitting the above-describedcarrier sleep command or the L1 CA control information may beidentically or similarly applied to the method for transmitting suchcarrier awake command.

5. The usage status of a specific carrier may be notified to the userequipment by using a method of configuring additional carriers, apartfrom the carrier(s) defined within the UE-specific carrier assignmentinformation, which is configured through UE-specific RRC signaling aswell as through control signaling respective to an individual carrier,such as carrier sleep. Alternatively, by transmitting an awake command,which ‘wakes up’ at least some of the carriers that are being operatedin a sleep mode, among the carriers that are defined within theUE-specific carrier assignment information, which is configured by usingUE-specific RRC signaling, the base station may indicate a usage statusof a specific carrier to the user equipment. In some cases, thesignaling method performed by using the above-described L1 CA controlinformation may be applied to both the carrier sleep command and thecarrier awake command.

1) The carrier sleep/awake command may be transmitted to the userequipment through a random carrier. Most particularly, however, due tothe characteristic of the awake command, the awake command may bedelivered to the user equipment through a predetermined carrier orthough a downlink primary carrier. By using this method, the signalingoverhead may be reduced.

2) Herein, it may be preferable that the carrier sleep/awake commandcorresponds to control information on a single carrier. However, thecarrier sleep/awake command may also simultaneously include the controlinformation respective to two or more carriers.

3) The format of the carrier sleep/awake command may be configured tohave the format through which the above-described L1 CA controlinformation may be delivered, or may be configured to have aCRC-protected message format.

4) The carrier sleep/awake operation may be initiated by both the userequipment and the base station.

5) The user equipment does not perform any processing on the carrier,which is in the carrier sleep mode, and when a randomly designated sleepmode period is ended, the corresponding carrier may once again besubject to processing (i.e., return to the normal mode operation). Thesleep mode may also be maintained until the next signaling withouthaving to set up a particular sleep mode period. Similarly, when arandomly designated awake mode period is ended, the correspondingcarrier may return to the sleep or off status. Also, the awake mode mayalso be maintained until the next signaling without having to set up aparticular awake mode period.

6) The methods proposed in the present invention with respect to the L1CA control information transmission may also be applied to thetransmission of the carrier awake/sleep mode.

Carrier Sleep/Awake

Hereinafter, the carrier sleep/awake status will be described in detail.

Information that is included in the L1 CA control information in orderto override the carrier assignment information, which is configured in aradio resource control layer, may correspond to information related to“carrier sleep” and/or “carrier awake”.

1) “Carrier sleep” corresponds to a function of turning off a specificcarrier for a predetermined period of time by using a signaling method,such as UE-specific radio resource control signaling. Herein, thespecific carrier is selected from one or more candidate carriersassigned to the user equipment, or from all available carriersconfigured in the base station. When the carrier is turned off, the userequipment does not perform any processing operations (e.g., monitoringof the control channel) on the corresponding carrier. In an example of acarrier sleep, among n number of carriers, which is semi-staticallyassigned to a specific user equipment (UE), the user equipment may turnoff k number of carriers (k≦n) for a time period of t1 (t1≦T, T=radioresource control signaling transmission cycle period). At this point,among the carriers that may correspond to the subject carrier that is tobe turned off, a method preventing carrier sleep from being applied tothe specifically configured carrier or the primary carrier may also beused.

Hereinafter, the carrier sleep (deactivation) status will now bedescribed in more detail.

When a plurality of downlink component carriers and/or a plurality ofuplink component carriers, which are configured by a random cell (orrelay station node), exist, activation/deactivation may be performed onrandom carriers, which is configured by the corresponding cell, or maybe performed on random carriers, which are already assigned in order toUE-specifically or cell-specifically transmit physical channels andphysical signals. In a situation where random downlink carriers aredeactivated, downlink synchronization does not occur, and, in somecases, channel measurement may not occur as well. Such channelmeasurement may essentially refer to a second layer measurement (L2measurement: channel quality indicator/precoder matrix indicator/rankindicator or channel status information). However, in some cases, athird layer measurement (L3 measurement: RSRP/RSRQ) may not be performedas well. Herein, the deactivation of random downlink carriers may referto a situation in which the cell (or relay station node as a downlinktransmission subject) does not transmit a physical downlink channel(PDCCH and/or PDSCH) to a specific user equipment or all userequipments, or the deactivation of random downlink carriers may refer toa situation in which a user equipment (or relay station node as adownlink reception subject) does not prepare or expect to receive aphysical downlink channel (PDCCH and/or PDSCH). When random uplinkcarriers are deactivated, uplink synchronization is not performed, and,in some cases, channel measurement (SRS transmission) is not performedas well. Herein, the deactivation of random uplink carriers may refer toa situation in which a user equipment (or relay station node as anuplink transmission subject) does not transmit a physical uplink channel(PUCCH and/or PUSCH), or the deactivation of random uplink carriers mayrefer to a situation in which a cell (or relay station node as an uplinkreception subject) does not prepare or expect to receive a physicaluplink channel (PUCCH and/or PUSCH).

Hereinafter, the operations of a user equipment in a carrier sleep(deactivation) mode will now be described in detail.

Physical downlink control channel (PDCCH) based L1 CA controlinformation may be dynamically transmitted to a specific user equipmentor a user equipment group, or transmitted by using event-triggering, oran activation indicator of a specific carrier may be semi-staticallytransmitted to a specific user equipment or a user equipment group byusing higher layer signaling. Conversely, based upon the operations of aspecific cell, the user equipment may implicitly recognize theactivation of a specific carrier. As an example of such specific celloperation, a physical downlink control channel including generaldownlink carrier assignment information or a physical downlink controlchannel including uplink grant information does not schedule a physicaluplink/downlink shared channel transmission from the correspondingcarrier. By performing the above-described process, the user equipment,which has recognized the deactivation of the specific carrier,

After recognizing the deactivation of the specific carrier by performingthe above-described process, the user equipment does not perform anyfurther downlink reception detection or uplink physical signaltransmission for downlink or uplink synchronization with respect to thecorresponding carrier. At the same time, the user equipment does notreceive any of the physical channels and physical signals, whichcorrespond to reception targets, within the corresponding downlinkcarrier, and, in case of the uplink carrier, none of the physicalchannels and none of the physical signals are transmitted. Herein, whenit is said that all physical channels and physical signals correspondingto the reception target are not received, this may indicate that theuser equipment does not perform blind decoding of the physical downlinkcontrol channel and buffering of all physical signals and physicalchannels.

In such deactivation situation, in order to detect a physical downlinkcontrol channel for realizing activation or to detect a physicaldownlink control channel, which implicitly includes downlink channelassignment scheduling information or uplink grant information, a timesection (e.g., sub-frame unit) enabling the user equipment toperiodically and automatically monitor a control channel for apredetermined period of time may be designated, or a pattern using thedesignated time section may be designated. At this point, a downlinksynchronization process for periodically monitoring the physicaldownlink control channel within the deactivation section, may be definedduring or immediately before the time section, in which the controlchannel is being monitored by using the above-described monitoringpattern.

Alternatively, during a deactivation section of the correspondingcarrier, an idle state may be continuously maintain without having toconfigure the above-described periodic physical downlink control channelmonitoring section. At this point, the operation performed by the userequipment for detecting a physical downlink control channel in order torealize activation or for detecting a physical downlink control channel,which implicitly includes downlink channel assignment schedulinginformation or uplink grant information, may be performed by anotherdownlink component carrier, which is in an activated state. Accordingly,this is advantageous in the aspect of reception complexity and powerconsumption in the user equipment.

2) A “carrier awake” command may correspond to a function of beingadditionally assigned with a specific carrier, which is not assigned tothe user equipment, for a limited period of time by using a signalingmethod, such as UE-specific radio resource control signaling. Or, the“carrier awake” command may correspond to a function of activating onceagain a specific carrier, which had been deactivated by a sleep command,among multiple candidate carriers that are assigned to the userequipment by using UE-specific radio resource control signaling. Forexample, among n number of carriers, which is semi-statically assignedto a specific user equipment (UE), k number of carriers (k≦n) may beturned off for a time period of t1 (t1≦T, T=radio resource controlsignaling transmission cycle period).

Hereinafter, the carrier awake (or activation) status will now bedescribed in more detail.

When a plurality of downlink component carriers and/or a plurality ofuplink component carriers, which are configured by a random cell (orrelay station node), exist, activation/deactivation may be performed onrandom carriers, which is configured by the corresponding cell, or maybe performed on random carriers, which are already assigned in order toUE-specifically or cell-specifically transmit physical channels andphysical signals. In a situation where random downlink carriers areactivated, downlink synchronization and channel measurement (L2measurement: CQI/PMI/RI and/or CSI (channel status information) or L3measurement (RSRP/RSRQ)) may be performed through the correspondingcarrier. Additionally, the carrier activation state may refer to astate, wherein each physical channel (physical downlink control channeland/or physical downlink shared channel) is transmitted by a cell (orrelay station node as a downlink transmission subject), and wherein auser equipment (or relay station node as a downlink reception subject)may receive the transmitted physical channel. When an uplink carrier isactivated, uplink synchronization and channel measurement are performed.Herein, the user equipment (or relay station node as an uplinktransmission subject) may always transmit a physical uplink channel(PUCCH and/or PUSCH), and a cell (or relay station node as an uplinkreception subject) may always received the transmitted physical uplinkchannel.

Hereinafter, the operations of a user equipment in a carrier awake modewill now be described in detail.

Physical downlink control channel (PDCCH) based L1 CA controlinformation may be dynamically transmitted to a specific user equipmentor a user equipment group, or transmitted by using event-triggering, oran activation indicator of a specific carrier may be semi-staticallytransmitted to a specific user equipment or a user equipment group byusing higher layer signaling. Conversely, based upon the operations of aspecific cell, the user equipment may implicitly recognize theactivation of a specific carrier. As an example of such specific celloperation, a physical downlink control channel including generaldownlink carrier assignment information or a physical downlink controlchannel including uplink grant information does not schedule a physicaluplink/downlink shared channel transmission from the correspondingcarrier. By performing the above-described process, the user equipment,which has recognized the deactivation of the specific carrier, may,first of all, search for a downlink synchronization signal (PSCH orSSCH) and perform channel estimation by using a reference signal (RS),so as to realize downlink or uplink synchronization of the correspondingcarrier, or the user equipment may perform a process of transmitting aphysical signal so as to realize uplink synchronization. This maycorrespond to an initial process during an actual activation mode, ormay correspond to a process immediately before the transition from anactivation mode to a deactivation mode. In a situation where thedownlink or uplink synchronization is realized, the user equipment mayreceive all physical channels and physical signals, which correspond tothe reception targets within a downlink, and, in case of an uplink, theuser equipment may transmit the required physical channels and physicalsignals.

Hereinafter, a detailed example of the L1 CA control information as theabove-described carrier sleep/awake command will now be described withreference to FIG. 7.

FIG. 7 illustrates exemplary carrier sleep/awake operations according toan exemplary embodiment of the present invention.

Referring to FIG. 7, a valid time t1 indicates a time period, which isconfigured from a transmission sub-frame of the lower-layer carrieraggregation control information, i.e., L1 CA control information.However, this is merely exemplary, and, therefore, the valid time t1 mayalso indicate an offset starting from a transmission sub-frame of the L1CA control information according to the present invention, during thetransmission performed by the user equipment or cell/base station, to apoint where the carrier aggregation state of the correspondinginformation is applied. Based upon a confirmation on the above-describedL1 CA control information, p(≧0) or q(≧0) number of sub-frames gapsrespective to whether or not a confirmation process is performed may beincluded in the valid time. Conversely, the starting point of a durationof the valid time t1 may be configured immediately after the p(≧0) orq(≧0) number of sub-frames gaps. In defining a valid section of theabove-described L1 CA control information, a method of transmitting aseparate set of L1 CA control information for configuring as well ascancelling the valid section may be applied. At this point, the proposedmethod for transmitting the above-described L1 CA control informationmay be applied in order to transmit the L1 CA control information.

The configuration, transmission format, and information properties ofthe L1 CA control information disclosed herein may be applied as theconfiguration, transmission format, and information properties of theinformation being transmitted via UE-specific radio resource controlsignaling transmission, the information being used as the UE-specific orUE-group-specific carrier assignment information. Conversely, theconfiguration and information properties of the UE-specific radioresource control signaling information, which is used as the UE-specificor UE-group-specific carrier assignment information, may follow theconfiguration, transmission format, and information properties of the L1CA control information.

Hereinafter, as another embodiment of the present invention, the mobilestation and base station, wherein the above-described embodiments of thepresent invention may be performed will be described in detail.

The mobile station may operate as a transmitter in the uplink and mayoperate as a receiver in the downlink. Also, the base station mayoperate as a receiver in the uplink and may operate as a transmitter inthe downlink. More specifically, the mobile station and the base stationmay include a transmitter and a receiver so as to transmit informationor data.

The transmitter and the receiver may include a processor, a module, apart and/or means for performing the embodiments of the presentinvention. Particularly, the transmitter and the receiver may include amodule (or means) for encoding (or encrypting) a message, a module forinterpreting an encoded (or encrypted) message, an antenna fortransmitting and receiving messages, and so on. An example of suchtransmitting end and receiving end will be described in detail withreference to FIG. 8.

FIG. 8 illustrates a block view showing exemplary structures of atransmitting end and a receiving end according to another exemplaryembodiment of the present invention.

Referring to FIG. 8, the left side represents the structure of thetransmitting end, and the right side represents the structure of thereceiving end. Each of the transmitting end and the receiving end mayinclude an antenna (5, 10), a processor (20, 30), a transmission module(Tx module) (40, 50), a receiving module (Rx module) (60, 70), and amemory (80, 90). Each element may perform its corresponding function.Hereinafter, each element will now be described in detail.

The antenna (5, 10) either transmits a signal created from the Tx module(40, 50) to the outside, or receives a wireless signal from the outside,thereby delivering the received signal to the Rx module (60, 70). When aMultiple-Input Multiple-Output (MIMO) antenna function is supported, atleast 2 or more antennae may be provided herein.

The above-described antenna, the Tx module, and the Rx module maycollectively configure a wireless communication (or radio frequency(RF)) module.

The processor (20, 30) generally controls the overall operations of thetransmitting end or the receiving end. Most particularly, in the multiband environment described according to the exemplary embodiments of thepresent invention, the processor of the mobile terminal (or equipment)controls the overall operations of the user equipment, which arerequired to perform the initial access procedure, the reception ofcarrier assignment information following the initial access procedure,and the operation and management of carriers in accordance with theassignment information. Thus, the processor may be capable of exchangingdata with the base station and the relay station.

For example, the processor may control the reception module, so that thereceiving module can receive a broadcast channel and system informationof one or more downlink component carriers from the base station or therelay station, and so that a reference downlink component carrier can beconfigured, and so that an uplink component carrier that is linked tothe configured downlink component carrier can be determined.Accordingly, the processor may select a preamble from a random accesschannel preamble set, which is indicated by a physical random accesschannel parameter of the broadcast channel. Then, the processor maycontrol the transmission so that the selected preamble can betransmitted to the base station through an uplink component carrier.

Furthermore, the processor may receive UE-specific/UE-group-specificcarrier assignment information through a higher layer signaling (e.g.,radio resource control signaling) so as to determine its availablecarrier. Also, the processor may receive the L1 CA control informationso as to control the system so that the base station can performcommunication by using a carrier, which is modified (or changed)regardless of the carrier assignment information.

Herein, the higher layer signaling, the format, content, andtransmission methods of the L1 CA control information are similar tothose described above according to an exemplary embodiment of thepresent invention. Therefore, a detailed description of the same will beomitted for simplicity.

Meanwhile, the processor of the base station may determine the downlinkcomponent carrier to which the user equipment attempts to performinitial access, based upon the contents and/or received timing ofmessage 1 or message 3, which are transmitted from the user equipment.Also, by transmitting UE-specific/UE-group-specific carrier assignmentinformation to the user equipment, the processor may notify theavailable carrier information. Furthermore, in order to support anasymmetrical carrier environment for an LTE-A user equipment, regardlessof the carrier assignment information, or in order to change an on/offstate of the carrier assigned to the user equipment, the processor ofthe base station may transmit L1 CA control information to the userequipment by using a dedicated signaling method.

The Tx module (40, 50) may perform predetermined coding and modulationprocesses on the data scheduled by the processor (20, 30) and to betransmitted to the outside, thereby delivering the processed data to theantenna (10).

The Rx module (60, 70) may perform decoding and demodulation processeson a wireless signal received from the outside through the antenna (5,10), so as to recover the processed data to the original (or initial)state, thereby delivering the recovered data to the processor (20, 30).

A program for processing and controlling the processor (20, 30) may bestored in the memory (80, 90). The memory (80, 90) may also performfunctions for temporarily storing input/output data (in case of the userequipment, carrier assigned information, system information, temporarycell identifier, L1 CA control information, and so on, which areassigned to the user equipment by the base station). Furthermore, thememory (80, 90) may include at least one type of storage means, such asa flash memory type, a hard disk type, a multimedia card micro type, acard-type memory (e.g., SD or XD memory), a RAM (Random Access Memory),a SRAM (Static Random Access Memory), a ROM (Read-Only Memory), anEEPROM (Electrically Erasable Programmable Read-Only Memory), a PROM(Programmable Read-Only Memory), a magnetic memory, a magnetic disk, andan optical disk.

Meanwhile, the base station may perform a controller function forperforming the above-described embodiments of the present invention, anOFDMA (Orthogonal Frequency Division Multiple Access) packet scheduling,Frequency Division Duplex (TDD) packet scheduling, and channelmultiplexing functions, MAC frame variable control function based uponservice characteristics and frequency environment (or condition), ahigh-speed traffic real-time control function, a hand over function,authentication and encoding (or encryption) functions, packetmodulation/demodulation functions for transmitting data, a high-speedchannel coding function, and a real-time modem control function throughat least one of the above-described modules, or the base station mayfurther include a separate means, module, or part for performing suchfunctions.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the technical and essential spirit or scope ofthe invention. Therefore, the detailed description of the presentinvention should not be interpreted as limiting in all aspects of thepresent invention, but should be considered as exemplary. The scope ofthe appended claims of the present invention shall be decided based uponrational interpretation, and all modifications within the scope of theappended claims and their equivalents will be included in the scope ofthe present invention.

INDUSTRIAL APPLICABILITY

The method for efficiently transmitting and receiving controlinformation in a multi band environment and a user equipmentarchitecture for the same are described herein mostly based upon anexample that may be applied to a 3GPP LTE system. However, in additionto the 3GPP LTE system, the present invention may also be applied toother variety of mobile communication systems having the multi bandenvironment.

1-18. (canceled)
 19. A method for receiving carrier assignmentinformation by a user equipment (UE) in a wireless communication systemsupporting multiple carriers, the method comprising: transmitting, to abase station, UE capability information, the UE capability informationincluding a supportable bandwidth capability; receiving, from the basestation, carrier assignment information for the UE, the carrierassignment information being configured depending on the UE capabilityinformation, the carrier assignment information including informationrelated to at least one available candidate carrier configured for theUE; receiving, from the base station, a first carrier activation commandinstructing the UE to activate the at least one available candidatecarrier; activating the at least one available candidate carrier basedon the first carrier activation command; after the activating,receiving, from the base station, information related to at least oneadditionally added available candidate carrier; receiving, from the basestation, a second carrier activation command instructing the UE toactivate the at least one additionally added available candidatecarrier; activating the at least one additionally added availablecandidate carrier based on the second carrier activation command; andreceiving, from the base station, control information or data throughthe at least one available candidate carrier and the at least oneadditionally added available candidate carrier.
 20. The method of claim19, wherein the information related to at least one additionally addedavailable candidate carrier is received through a radio resource control(RRC) signaling.
 21. The method of claim 19, wherein the informationrelated to at least one additionally added available candidate carrierincludes carrier index information related to the at least oneadditionally added available candidate carrier.
 22. The method of claim19, wherein the first carrier activation command or the second carrieractivation command corresponds to a layer 2 (L2) signaling.
 23. Themethod of claim 19, wherein the carrier assignment information isreceived through a radio resource control (RRC) signaling.
 24. A userequipment (UE) for receiving carrier assignment information in awireless communication system supporting multiple carriers, the UEcomprising: a radio communication module; and a processor operativelyconnected to the radio communication module and configured to: controlthe radio communication module to transmit, to a base station, UEcapability information, the UE capability information including asupportable bandwidth capability; control the radio communication moduleto receive, from the base station, carrier assignment information forthe UE, the carrier assignment information being configured depending onthe UE capability information, the carrier assignment informationincluding information related to at least one available candidatecarrier configured for the UE; control the radio communication module toreceive, from the base station, a first carrier activation commandinstructing the UE to activate the at least one available candidatecarrier; activate the at least one available candidate carrier based onthe first carrier activation command; after the activating: control theradio communication module to receive, from the base station,information related to at least one additionally added availablecandidate carrier; and control the radio communication module toreceive, from the base station, a second carrier activation commandinstructing the UE to activate the at least one additionally addedavailable candidate carrier; activate the at least one additionallyadded available candidate carrier based on the second carrier activationcommand; and control the radio communication module to receive, from thebase station, control information or data through the at least oneavailable candidate carrier and the at least one additionally addedavailable candidate carrier.
 25. The UE of claim 24, wherein theinformation related to at least one additionally added availablecandidate carrier is received through a radio resource control (RRC)signaling.
 26. The UE of claim 24, wherein the information related to atleast one additionally added available candidate carrier includescarrier index information related to the at least one additionally addedavailable candidate carrier.
 27. The UE of claim 24, wherein the firstcarrier activation command or the second carrier activation commandcorresponds to a layer 2 (L2) signaling.
 28. The UE of claim 24, whereinthe carrier assignment information is received through a radio resourcecontrol (RRC) signaling.
 29. A method for receiving carrier assignmentinformation by a base station in a wireless communication systemsupporting multiple carriers, the method comprising: receiving, from auser equipment (UE), UE capability information, the UE capabilityinformation including a supportable bandwidth capability; transmitting,to the UE, carrier assignment information for the UE, the carrierassignment information being configured depending on the UE capabilityinformation, the carrier assignment information including informationrelated to at least one available candidate carrier configured for theUE; transmitting, to the UE, a first carrier activation commandinstructing the UE to activate the at least one available candidatecarrier; activating the at least one available candidate carrier basedon the first carrier activation command; after the activating,transmitting, to the UE, information related to at least oneadditionally added available candidate carrier; transmitting, to the UE,a second carrier activation command instructing the UE to activate theat least one additionally added available candidate carrier; activatingthe at least one additionally available candidate carrier and the addedavailable candidate carrier based on the second carrier activationcommand; and transmitting, to the UE, control information or datathrough the at least one available candidate carrier and the at leastone additionally added available candidate carrier.
 30. The method ofclaim 29, wherein the information related to at least one additionallyadded available candidate carrier is transmitted through a radioresource control (RRC) signaling.
 31. The method of claim 29, whereinthe information related to at least one additionally added availablecandidate carrier includes carrier index information related to the atleast one additionally added available candidate carrier.
 32. The methodof claim 29, wherein the first carrier activation command or the secondcarrier activation command corresponds to a layer 2 (L2) signaling. 33.The method of claim 29, wherein the carrier assignment information isreceived through a radio resource control (RRC) signaling.
 34. A basestation for receiving carrier assignment information in a wirelesscommunication system supporting multiple carriers, the base stationcomprising: a radio communication module; and a processor operativelyconnected to the radio communication module and configured to: controlthe radio communication module to receive, from a user equipment (UE),UE capability information, the UE capability information including asupportable bandwidth capability; control the radio communication moduleto transmit, to the UE, carrier assignment information for the UE, thecarrier assignment information being configured depending on the UEcapability information, the carrier assignment information includinginformation related to at least one available candidate carrierconfigured for the UE; control the radio communication module totransmit, to the UE, a first carrier activation command instructing theUE to activate the at least one available candidate carrier; activatethe at least one available candidate carrier based on the first carrieractivation command; after the activating: control the radiocommunication module to transmit, to the UE, information related to atleast one additionally added available candidate carrier; and controlthe radio communication module to transmit, to the UE, a second carrieractivation command instructing the UE to activate the at least oneadditionally added available candidate carrier; activate the at leastone additionally added available candidate carrier based on the secondcarrier activation command; and control the radio communication moduleto transmit, to the UE, control information or data through theavailable candidate carrier and the at least one additionally addedavailable candidate carrier.
 35. The base station of claim 34, whereinthe information related to at least one additionally added availablecandidate carrier is transmitted through a radio resource control (RRC)signaling.
 36. The base station of claim 34, wherein the informationrelated to at least one additionally added available candidate carrierincludes carrier index information related to the at least oneadditionally added available candidate carrier.
 37. The base station ofclaim 34, wherein the first carrier activation command or the secondcarrier activation command corresponds to a layer 2 (L2) signaling. 38.The base station of claim 34, wherein the carrier assignment informationis transmitted through a radio resource control (RRC) signaling.